Underground bioretention systems

ABSTRACT

Embodiments of the present invention provide underground bioretention systems that capture and treat surface water runoff. Such underground bioretention systems have a chamber formed by a chamber floor, a chamber ceiling, and at least one chamber wall; an access opening in the chamber ceiling fitted with an access opening cover; an influent opening in the chamber ceiling or the at least one chamber wall; an effluent opening positioned in the chamber floor or the at least one chamber wall beneath the influent opening; a filtration media positioned in the chamber beneath the influent opening; and an underdrain system positioned in proximity with the chamber floor. Also in such bioretention systems, the chamber floor, the chamber ceiling, and the at least one chamber wall are comprised of a material and a design adapted to form the chamber in a manner that withstands pressure applied thereon by subterranean and ground surface materials.

FIELD OF THE INVENTIONS

The present invention relates, in general, to water capture and treatment systems and methods of using the same. More particularly, the present invention relates to modular, underground biofiltration systems for developments where a sub-optimal or inadequate amount of surface area is available for biological treatment of stormwater prior to discharge from the property.

BACKGROUND OF THE INVENTIONS

Water treatment systems have been in existence for many years. These systems treat stormwater surface runoff or other polluted water. Stormwater runoff is of concern for two main reasons: i. volume and flow rate, and ii. pollution and contamination. The volume and flow rate of stormwater runoff is a concern because large volumes and high flow rates can cause erosion and flooding. Pollution and contamination of stormwater runoff is a concern because stormwater runoff flows into our rivers, streams, lakes, wetlands, and/or oceans. Pollution and contamination carried by stormwater runoff into such bodies of water can have significant adverse effects on the health of ecosystems.

The Clean Water Act of 1972 enacted laws to improve water infrastructure and quality. Sources of water pollution have been divided into two categories: point source and non-point source. Point sources include wastewater and industrial waste. Point sources are readily identifiable, and direct measures can be taken to mitigate them. Non-point sources are more difficult to identify. Stormwater runoff is the major contributor to non-point source pollution. Studies have revealed that contaminated stormwater runoff is the leading cause of pollution to our waterways. As we build houses, buildings, parking lots, roads, and other impervious areas, we increase the amount of water that runs into our stormwater drainage systems and eventually flows into rivers, lakes, streams, wetlands, and/or oceans. As more land becomes impervious, less rain seeps into the ground, resulting in less groundwater recharge and higher velocity flows, which cause erosion and increased pollution levels of watery environments.

Numerous sources introduce pollutants into stormwater runoff. Sediments from hillsides and other natural areas exposed during construction and other human activities are one source of such pollutants. When land is stripped of vegetation, stormwater runoff erodes the exposed land and carries it into storm drains. Trash and other debris dropped on the ground are also carried into storm drains by stormwater runoff. Another source of pollutants are leaves and grass clippings from landscaping activities that accumulate on hardscape areas and do not decompose back into the ground, but flow into storm drains and collect in huge amounts in lakes and streams. These organic substances leach out large amounts of nutrients as they decompose and cause large algae blooms, which deplete dissolved oxygen levels in marine environments and result in expansive marine dead zones. Unnatural stormwater polluting nutrients include nitrogen, phosphorus, and ammonia that come from residential and agricultural fertilizers.

Another major concern are heavy metals, which come from numerous sources and are harmful to fish, wildlife, and humans. Many of our waterways are no longer safe for swimming or fishing due to heavy metals introduced by stormwater runoff. Heavy metals include zinc, copper, lead, mercury, cadmium and selenium. These metals come from vehicle tires and brake pads, paints, galvanized roofs and fences, industrial activities, mining, recycling centers, etc. Hydrocarbons are also of concern and include include oils and grease. These pollutants come from leaky vehicles and other heavy equipment that use hydraulic fluid, brake fluid, diesel, gasoline, motor oil, and other hydrocarbon based fluids. Bacteria and pesticides are additional harmful pollutants carried into waterways by stormwater runoff.

Over the last 20 years, the Environmental Protection Agency (EPA) has been monitoring the pollutant concentrations in most streams, rivers, and lakes in the United States. Over 50% of waterways in the United States are impaired by one of more of the above-mentioned pollutants. As part of the EPA Phase 1 and Phase 2 National Pollutant Discharge Elimination Systems, permitting requirements intended to control industrial and non-industrial development activities have been implemented. Phase 1 was initiated in 1997 and Phase 2 was initiated in 2003. While there are many requirements for these permits, the main requirements focus on pollution source control, pollution control during construction, and post construction pollution control. Post construction control mandates that any new land development or redevelopment activities incorporate methods and solutions that both control increased flows of rain water off the site and decrease (filter out) the concentration of pollutants off the site. These requirements are commonly known as quantity and quality control. Another part of these requirements is for existing publicly owned developed areas to retrofit the existing drainage infrastructure with quality and quantity control methods and technologies that decrease the amount of rain water runoff and pollutant concentrations therein.

A major category of technologies used to meet these requirements are referred to as structural best management practices (BMPs). Structural BMPs include proprietary and non-proprietary technologies designed to store and/or remove pollutants from stormwater. Technologies such as detention ponds and regional wetlands are used to control the volume of runoff while providing some pollutant reduction capabilities. Over the past 10 years, numerous technologies have been invented to effectively store water underground, which frees up buildable land. Various rain water runoff treatment technologies such as catch basin filters, hydrodynamic separators, media filters are used to remove pollutants. These technologies commonly work by using the following processes: screening, separation, physical filtration, and chemical filtration.

SUMMARY OF THE INVENTIONS

Bio-swales, infiltration trenches, and bioretention areas, commonly known as low impact development (LID) have been implemented to both control flow volumes and remove pollutants on a micro level. LID technologies have also proven successful at removing difficult pollutants such as bacteria, dissolved nutrients, and metals because they provide not only physical and chemical, but also biological filtration processes. They do so by incorporating a living vegetation element that supports a microbial community which assists in pollutant removal. Biological filtration processes have proven excellent at removing many of the pollutants that physical and chemical filtration systems alone cannot.

Conventional LID technologies, however, require substantial amounts of space. For instance, a typical bioretention design takes up approximately 4% of the buildable area of any construction project. This space requirement translates into significant reductions in the amounts of parking spaces, and therefore building sizes that can be incorporated into construction projects. The significant amounts of space taken up by conventional stormwater biofiltration systems make it more expensive, and therefore less feasible, to develop property.

Embodiments of the present invention provide underground bioretention systems that capture and treat contaminated surface water runoff. Such underground bioretention systems have a chamber formed by a chamber floor, a chamber ceiling, and at least one chamber wall; an access opening in the chamber ceiling fitted with an access opening cover; an influent opening in the chamber ceiling or the at least one chamber wall; an effluent opening positioned in the chamber floor or the at least one chamber wall beneath the influent opening; a filtration media positioned in the chamber beneath the influent opening; and an underdrain system positioned in proximity with the chamber floor. Also in such bioretention systems, the chamber floor, the chamber ceiling, and the at least one chamber wall are comprised of a material and a design adapted to form the chamber in a manner that withstands pressure applied thereon by subterranean and ground surface materials that surround the underground bioretention system and that are at least one material selected from the group consisting of a subterranean soil, a subterranean rock, a ground surface pervious material, and a ground surface impervious material.

In some embodiments, the underground bioretention system further comprises live vegetation in the filtration media. In some embodiments, the underground bioretention system further comprises mulch above the filtration media. In some embodiments, the underground bioretention system further comprises a rock backfill in proximity with the underdrain system. In some embodiments, the underground bioretention system further comprises a plant establishment media in proximity with a surface of the filtration media and live vegetation in the plant establishment media. In some embodiments, the underground bioretention system further comprises a splash guard positioned under the influent opening. In some embodiments, the underground bioretention system further comprises an inlet flow distributor and sedimentation chamber positioned under the influent opening. In some embodiments, the underground bioretention system further comprises a flow restrictor positioned in the underdrain system contains and operative to restrict a flow of water passing through the bioretention system. In some embodiments, the underground bioretention further comprises weep holes in the chamber floor. In some embodiments, the underground bioretention further comprises a bypass riser. In some embodiments, the underground bioretention system further comprises an irrigation system. In some embodiments, the underground bioretention system further comprises an access riser and a reflective material mounted on an inner surface of at least one of a wall of the access riser and the at least one chamber wall, wherein the access opening cover is adapted to allow natural light to enter the chamber. In some embodiments, the underground bioretention system further comprises an artificial light operative to emit an amount of light energy that promotes a growth of the live vegetation. In some embodiments, the underground bioretention system further comprises at least one of a battery and a solar panel operative to supply electrical power to the artificial light.

In some embodiments, the underground bioretention filtration media is placed over a layer of matrix underdrain structure. In some embodiments, the filtration media is at least one member selected from the group consisting of an inert material and a cation exchange material. Some embodiments of the present invention provide underground bioretention systems that capture and treat contaminated surface water runoff. Such underground bioretention systems have a first chamber formed by a first chamber floor, a first chamber ceiling, and at least one first chamber wall and a second chamber formed by a second chamber floor, a second chamber ceiling, and at least one second chamber wall. In such bioretention systems, at least one of the first chamber ceiling and the second chamber ceiling further comprises an access opening fitted with an access opening cover; at least one of the first chamber ceiling or the at least one first chamber wall and the second chamber ceiling or the second chamber wall further comprises an influent opening; at least one of the first chamber floor or the at least one first chamber wall and the second chamber floor or the second chamber wall further comprises an effluent opening, the second chamber comprises a filtration media in proximity with the second chamber floor and an underdrain system in proximity with the second chamber floor; and the at least one first chamber wall further comprises a first coupling opening and the at least one second chamber wall further comprises a second coupling opening, the first coupling opening and the second coupling opening are fitted together in a manner that places the first chamber and the second chamber in substantially leak-free fluid communication, the influent opening and the effluent opening are not both positioned in the first chamber or the second chamber, the first chamber floor, the first chamber ceiling, and the at least one first chamber wall are comprised of a material and a design adapted to form the first chamber in a manner that withstands pressure applied thereon by subterranean and ground surface materials that surround the underground bioretention system and that are at least one material selected from the group consisting of a subterranean soil, a subterranean rock, a ground surface pervious material, and a ground surface impervious material, and the second chamber floor, the second chamber ceiling, and the at least one second chamber wall are comprised of a material and a design adapted to form of the chamber in a manner that withstands pressure applied thereon by subterranean and ground surface materials that surround the underground bioretention system and that are at least one material selected from the group consisting of a subterranean soil, a subterranean rock, a ground surface pervious material, and a ground surface impervious material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an underground bioretention system according to the present invention equipped with a perforated pipe underdrain system.

FIG. 2 is a side view of an underground bioretention system according to the present invention equipped with a matrix underdrain structure.

FIG. 3 is a side view of an underground bioretention system according to the present invention equipped with a perforated pipe underdrain system and weep holes.

FIG. 4 is side view of an underground bioretention system according to the present invention equipped with a perforated pipe underdrain system, a splash guard, and a vertical riser.

FIG. 5 is a side view of an underground bioretention system according to the present invention equipped with a mulch layer, a perforated pipe underdrain system, and rock backfill.

FIG. 6 is a side view of an underground bioretention system according to the present invention equipped with a perforated pipe underdrain system, a vertical riser, living vegetation, artificial lights, and an irrigation system.

FIG. 7 is a side view of an underground bioretention system according to the present invention equipped with a matrix underdrain system, living vegetation planted in plant establishment media, and natural light sources.

FIG. 8 is a side view of an underground bioretention system according to the present invention equipped with a perforated pipe underdrain system and a pre-treatment and even distribution channel.

FIG. 9 is a side view of a multi-chamber underground bioretention system according to the present invention equipped with a perforated pipe underdrain system.

FIG. 10 is a side view of an underground bioretention system according to the present invention equipped with a pre-treatment chamber and a treatment chamber equipped with a perforated pipe underdrain system, living vegetation, artificial lights, and a solar panel that supplies electricity to the artificial lights.

DETAILED DESCRIPTION OF THE INVENTIONS

Referring to FIG. 1, an underground bioretention system 10 to capture and treat stormwater and contaminated runoff water is shown. The system is designed to be utilized in urbanized or other developed areas where the majority of land is impervious. The system may be placed adjacent to any impervious area which generates rain water runoff or runoff of other contaminated waters from its surface. The system may also connect directly with specific point sources of contaminated waters. With limited surface area in most urban areas for biological filtration systems, the system itself is placed underground. The underground placement of bioretention system 10 provides surface area space that may be used for new construction and/or expansion of buildings, parking lots, roadways, etc. in urban areas.

At the center of the underground bioretention system 10 is chamber 100. The chamber 100 has a floor 130, ceiling 110, and walls 120. The modular design of bioretention systems according to the present invention allows the system to scale to various sizes and shapes. The chambers of bioretention systems according to the present invention are generally square or rectangular in shape, but they may be circular or triangular in shape as needed for particular installation sites. Referring again to FIG. 1, the chamber walls 120, floor 130, and ceiling 110 are made of material that is impermeable to water; and their material and design must withstand inside pressure from water running through and accumulating in the chamber 100. Underground bioretention system 10 is structurally sound to withstand outside pressure from soil 230 on the sides and top, as well as paved surfaces 200. There is also the additional pressure on top of underground bioretention system 10 from the weight of vehicular traffic 50. In some embodiments of bioretention systems according to the present invention, the chamber walls 120, floor 130, and ceiling 110 are made of strong, durable, and water impermeable material including, but not limited to, concrete, metal, plastic, and fiberglass. In some embodiments, a ground surface above an installed underground bioretention system comprises a water pervious material that is one or more of porous asphalt, porous concrete, porous brick, porous tile, gravel, and soil. In some embodiments, a ground surface above an installed an underground bioretention system comprises a water impervious material that is one or more of asphalt, concrete, brick, flagstone and tile.

Referring again to FIG. 1, stormwater or other surface water runoff enters the chamber 100 from the inflow pipe 300 and an influent opening in chamber wall 120 receives inflow pipe 300. In some embodiments, the walls and/or ceilings of a bioretention system chamber have multiple influent openings. In some embodiments, the ceiling of a bioretention system chambers has at least one grated influent opening that allows water to flow into the chamber but prevents people, vehicles, etc. from falling into the chamber. In some embodiments, at least one influent opening in a wall of an underground bioretention system chamber is covered by a screening, grating, or netting that allows water and fine sediments to flow into the chamber and impedes larger rocks and other debris from entering the chamber.

Referring again to FIG. 1, water flows from the inflow pipe 300 down into the filtration media 600. The filtration media 600 is the treatment mechanism of the underground bioretention system, and provides the primary treatment of passing water. In some embodiments, the filtration media comprises at least one inert material such as sand and gravel and at least one cation exchange material such as organic matter that includes, but is not limited to, wood chips, compost, and peat moss. Such organic matter removes dissolved metals and other pollutants by supporting chemical reactions. Other particulate pollutants and hydrocarbons are physically trapped between the inert and cation exchange material within the filtration media 600. In some embodiments, the filtration media comprises inorganic cation exchange media such as zeolite, expanded aggregates, lava rock, oxide-coated inert material, alumina, pumice, and other similar oxides. In some embodiments, inorganic cation exchange materials may be preferred over organics because they are less likely to leach nutrients such as dissolved phosphorous or nitrogen, which have a negative effect on the performance of the system. In some embodiments, the filtration media may comprise 100% cation exchange media. Filtration media layers in bioretention systems of the present invention can be from a few inches to several feet thick.

Referring again to FIG. 1, after passing water is treated through the filtration media 600, it enters the underdrain system 340. The underdrain system 340 is a perforated pipe laid horizontally underneath the filtration media 600 and above the chamber floor 130. The perforated pipe extends the length of the chamber floor 130. Water that enters the underdrain system 340 exits out of the bioretention system 10. In some embodiments, underdrain systems are formed from veins of large granular material installed in the filtration media, from a panel separated from the filtration media by netting, or a combination thereof. In some embodiments, water that enters the underdrain system exits the bioretention system through an effluent opening in a chamber wall or floor.

Referring again to FIG. 1, there is an access opening cover 500 located in the ceiling 110 of underground bioretention system 10. The access opening cover 500 is designed to allow personnel to enter the chamber 100 and perform any necessary maintenance or monitoring. Access opening cover 500 is designed to prevent people, animals, cars, and other large objects from falling into the chamber 100 and is structurally strong enough to support the weight of vehicular traffic. Access opening cover 500 is substantially smooth and flush with the pervious surface 200 so that it does not damage vehicular traffic 50. When placed underground, the bioretention system 10 may be covered with soil 230 and a pervious surface 200. Since there is a layer of soil 230 between the chamber ceiling 110 and pervious surface 200, the underground bioretention system 10 comprises access riser 530 between the chamber 100 and the access opening cover 500.

In some embodiments, access opening covers comprise a solid hatch that prevents water from entering into the chamber. In some embodiments, access opening covers comprise a grate that prevents pedestrians and vehicles from entering the chamber, but allows stormwater or other surface water runoff to enter the chamber.

FIG. 2 illustrates an underground bioretention system 10 that differs from the bioretention system illustrated in FIG. 1 by comprising an underdrain system 380 that is formed from a vein of pervious matrix material in the filtration media 600. In the bioretention system 10 illustrated in FIG. 2, the pervious matrix material in the underdrain system 380 supports the weight of the filtration media 600. In some embodiments, matrix underdrain systems comprise a matrix material having at least 50% void space to allow passing water that enters it to exit the underground bioretention system 10.

FIG. 3 illustrates an underground bioretention system 10 that differs from the bioretention system illustrated in FIG. 1 by further comprising weep holes 160 located in chamber floor 130 that allow water to exit through the bottom of the underground bioretention system 10 and infiltrate into the native soil below. After treatment by the filtration media 600, passing water may either enter into the underdrain system 340 and then exit underground bioretention system 10 or enter into weep holes 160 and then exit underground bioretention system 10.

FIG. 4 illustrates an underground bioretention system 10 that differs from the bioretention system illustrated in FIG. 1 by further comprising a splash guard 640 and bypass riser 370. In the underground bioretention system 10 illustrated in FIG. 4, stormwater or other surface water runoff enters chamber 100 through inflow pipe 300. Splash guard 640 is installed below inflow pipe 300 and on top of filtration media 600 such that it slows down high velocity water entering the chamber 100 and thereby inhibits water entering chamber 100 from removing or displacing filtration media 600. In some embodiments, splash guards are comprised of scour pads and/or riprap. In some embodiments, a splash guard is placed below an access opening that allows water to enter into the chamber.

Referring again to FIG. 4, the perforated pipe underdrain system 340 contains, inside the perforated pipe, a flow restrictor plate which has a smaller diameter than the perforated pipe and is sized to control the flow of water out of the underdrain such that passing water flows through the filtration media 600 at a slower rate that remains substantially the same, even when the filtration media 600 begins to clog with sediments and/or hydrocarbons. By extending the amount of time passing water spends in filtration media 600, the flow restricted perforated pipe underdrain system 340 enhances the contaminated water treatment performance of the underground bioretention system 10.

Referring again to FIG. 4, the bypass riser 370 also controls water levels in and flow through the chamber 100. The bypass riser 370 connects to the perforated pipe of the underdrain system 340, extends vertically above the filtration media 600, and has an open top. Although the bypass riser 370 connects with the restricted flow perforated pipe of the underdrain system 340, bypass riser 370 is not flow restricted, but rather provides for high water flow rates. Accordingly, during times that water flows into the chamber 100 at rates that do not exceed the maximum water flow rate through filtration media 600, passing water flows through filtration media 600 and exits the biofiltration system 10 through the perforated pipe underdrain system 340. During times that water flows into the chamber 100 at rates that exceed the maximum water flow rate through filtration media 600, water levels rise in chamber 100. When water levels in chamber 100 rise above the level of the open top of bypass riser 370 some passing water flows through bypass riser 370 and out of the bioretention system 10, thereby bypassing filtration media 600.

FIG. 5 illustrates an underground bioretention system 10 that differs from the bioretention system illustrated in FIG. 1 by further comprising a layer of mulch 620 and rock backfill 610. In the bioretention system 10 illustrated in FIG. 5, mulch 620 pre-treats water entering the chamber 100 prior to entering filtration media 600. The mulch 620 in the bioretention system 10 is illustrated in FIG. 5 is laid on top of filtration media 600. Mulch 620 captures and retains pollutants, while at the same time preventing the pollutants from coming into contact with filtration media 600, thereby reducing the rate at which pollutants clog filtration media 600 and extending the time that can pass between servicing underground bioretention filtration system 10.

The rock backfill 610 is placed directly under filtration media 600 and placed evenly around the perforated pipe of the underdrain system 340. So placed, rock backfill 610 enhances the transfer of passing water from the filtration media 600 to the perforated pipe of the underdrain system 340.

FIG. 6 illustrates an underground bioretention system 10 that differs from the bioretention system illustrated in FIG. 1 by further comprising living vegetation 700, artificial lights 800, and an irrigation system 720. Living vegetation 700 is planted and grown in the filtration media 600. The roots of living vegetation 700 transfer oxygen into filtration media 600, promoting the establishment of beneficial microorganism colonies that actively aid in the break down of nutrients, hydrocarbons, and other harmful pollutants in passing water. The roots of living vegetation 700 themselves can uptake some of the pollutants through the process of bioaccumulation. The roots of living vegetation 700 can also utilize nutrients for growth, thus reducing polluting nutrient levels in passing water. Artificial lights 800 are installed in chamber ceiling 130 to ensure living vegetation 700 survive, sustain, and thrive. Artificial lights 800 provide necessary energy to for living vegetation to perform photosynthesis in a subterranean environment.

In some embodiments, living vegetation in underground bioretention systems according to the invention are one or more of plants, bacteria, and fungi. In some embodiments, artificial lights are installed into chamber walls of bioretention systems according to the present invention. In some embodiments, artificial lights used in bioretention systems according to the present invention are one or more of a florescent light, a high pressure sodium light, a metal halide light, and a light emitting diode. Florescent lights provide moderate amounts of light spectrum range and output to support plant growth. High pressure sodium and metal halide provide high amounts of light spectrum range and output appropriate for plant growth. In recent years, an array of blue and red light emitting diodes have been used to provide the same benefits of high pressure sodium and metal halide lights; but with less power usage, making them an environmentally and financially sound option. In some embodiments, lights are available with ballasts that allow for air venting with fans to remove excessive heat. In some embodiments, such artificial light ballasts are waterproof to provide an additional level of safety. Artificial lights used in some embodiments of the present invention are powered by electricity supplied by one or more of the grid, solar panels, or batteries.

Referring again to FIG. 6, irrigation system 720 provides water to living vegetation 700 at times when surface water runoff is insufficient to support living vegetation 700. Irrigation system 720 is a drip system that is routed from outside underground bioretention system 10 to the inside through side wall 120. Irrigation system 720 has drip tubing that provides water to living vegetation at a rate that is beneficial to living vegetation 700. In some embodiments of underground bioretention systems of the present invention, an underground cistern is located nearby that holds water treated by the underground bioretention system and stores it for irrigation. In some embodiments, irrigation systems installed into bioretention systems are powered with electricity supplied by one or more of the grid, solar panels, and batteries.

FIG. 7 illustrates an underground bioretention system 10 that differs from the bioretention system illustrated in FIG. 2 by further comprising plant propagation media 740, live vegetation 700, and riser 530 lined with reflective material 820. In the bioretention system illustrated in FIG. 7, natural light 850 enters the chamber 100 through grated access opening cover 500 and access riser 530, which is lined with reflective material 820 to increase the amount of natural light 850 that reaches living vegetation 700. In some embodiments of bioretention systems of the invention that use natural light to assist plant growth, one or more reflective material(s) line one or more of the access riser walls and the chamber walls. Examples of reflective materials include, but are not limited to, glass, light colored paint, tin foil, biaxially-oriented polyethylene terephthalate, plastic, or polished materials.

FIG. 8 illustrates an underground bioretention system 10 differs from the bioretention system illustrated in FIG. 1 by further comprising an inlet flow distributor and sedimentation chamber 310. The inlet flow distributor and sedimentation chamber 310 is placed so that the top portion is just below the inflow pipe 300 and access opening cover 500. The inlet flow distributor and sedimentation chamber 310 captures stormwater and other surface water runoff that flows into the chamber 100, allowing sediments to fall out as well as allowing water to distribute evenly into filtration media 600. The inlet flow distributor and sedimentation chamber 310 contains a vertical drain down riser 330 connected to drain down line 320. The drain down line 320 extends into filtration media 600 allowing water to enter the inlet flow distributor and sedimentation chamber 310 to drain during periods in which no water is entering the chamber 100. Water exits out of the chamber 100 through the underdrain system 340. In some embodiments of bioretention filtration systems of the present invention, vertical drain down risers are wrapped in a filter netting or fabric.

FIG. 9 illustrates an underground bioretention system 10 comprising two chambers 100 interconnected. Interconnected chambers 100 are joined by one or more holes or windows in side wall 120 where the chambers 100 meet.

FIG. 10, illustrates an underground bioretention system 10 comprising chamber 100 and pre-treatment chamber 180. Stormwater or other surface runoff water enters into pre-storage chamber 180 from inflow pipe 300. The pre-storage chamber 180 contains no filtration media or living vegetation, but rather allows sediment to settle out of passing water before it enters chamber 100. Passing water transfers to chamber 100 with filtration media 600 and living vegetation 700 when water levels in pre-treatment chamber 180 rise above the height of bottom of the connecting hole or window in side walls 120. Passing water that enters chamber 100 is treated by living vegetation 700 and filtration media 600. From there, passing water percolates into the perforated pipe of underdrain system 340 and exits the bioretention system 100. Artificial lights 800 powered by electricity supplied by an external solar panel system 900 provide light energy for living vegetation 700.

In some embodiments, underground bioretention structures are built to handle site specific loading conditions. Surface loads applied to underground bioretention systems vary based upon pedestrian and vehicular traffic, and can be broken down into the following categories. Parkway loading includes sidewalks and similar areas that are adjacent to streets and other areas with vehicular traffic. Indirect traffic loading includes areas that encounter daily low speed traffic from vehicles ranging from small cars up to semi-trucks. Direct traffic loading includes areas, such as streets and other parkways, that encounter a high volume of high speed traffic from vehicles ranging from small cars to large semi-trucks. There is also heavy duty equipment loading that includes traffic from, e.g., airplanes and heavy port equipment. Accordingly, underground bioretention systems of the present invention may be constructed having walls, floors, and/or ceilings of various thicknesses and strengths (e.g., differing thicknesses of concrete or steel or differing amounts of rebar) such that they achieve a parkway load rating (e.g., a H5 load rating), an indirect traffic load rating (e.g., a H20 load rating), a direct traffic load rating (e.g., a H20 load rating), or a heavy duty equipment load rating (e.g., a H25 load rating), as required for a given installation site.

Although the disclosure has been provided in the context of certain embodiments and examples, it will be understood by those skilled in the art that the disclosure extends beyond the specifically described embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. Accordingly, the disclosure is not intended to be limited by the specific disclosures of embodiments herein. 

What is claimed is:
 1. An underground bioretention system, to capture and treat contaminated surface water runoff, comprising: a chamber formed by a chamber floor, a chamber ceiling, and at least one chamber wall; an access opening in the chamber ceiling fitted with an access opening cover; an influent opening in the chamber ceiling or the at least one chamber wall; an effluent opening positioned in the chamber floor or the at least one chamber wall beneath the influent opening; a filtration media positioned in the chamber beneath the influent opening; and an underdrain system positioned in in proximity with the chamber floor, and wherein the chamber floor, the chamber ceiling, and the at least one chamber wall are comprised of a material and a design adapted to form the chamber in a manner that withstands pressure applied thereon by subterranean and ground surface materials that surround the underground bioretention system.
 2. The underground bioretention system of claim 1, further comprising live vegetation in the filtration media.
 3. The underground bioretention system of claim 1, further comprising a mulch above the filtration media.
 4. The underground bioretention system of claim 1, further comprising a rock backfill in proximity with the underdrain system.
 5. The underground bioretention system of claim 1, wherein the filtration media is placed over a layer of matrix underdrain structure.
 6. The underground bioretention system of claim 1, further comprising a plant establishment media in proximity with a surface of the filtration media and live vegetation in the plant establishment media.
 7. The underground bioretention system of claim 1, further comprising a splash guard positioned under the influent opening.
 8. The underground bioretention system of claim 1, further comprising an inlet flow distributor and sedimentation chamber positioned under the influent opening.
 9. The underground bioretention system of claim 1, further comprising a flow restrictor, and wherein the flow restrictor is positioned in the underdrain system and operative to restrict a flow of water passing through the bioretention system.
 10. The underground bioretention system of claim 1, further comprising weep holes in the chamber floor.
 11. The underground bioretention system of claim 1, further comprising a bypass riser.
 12. The underground bioretention system of claim 1, wherein the filtration media is at least one member selected from the group consisting of an inert material and a cation exchange material.
 13. The underground bioretention system of claim 2, further comprising an irrigation system.
 14. The underground bioretention system of claim 2, further comprising an access riser and a reflective material mounted on an inner surface of at least one of a wall of the access riser and the at least one chamber wall, wherein the access opening cover is adapted to allow natural light to enter the chamber.
 15. The underground bioretention system of claim 2, further comprising an artificial light operative to emit an amount of light energy that promotes a growth of the live vegetation.
 16. The underground bioretention system of claim 15, further comprising at least one of a battery and a solar panel operative to supply electrical power to the artificial light.
 17. An underground bioretention system, to capture and treat contaminated surface water runoff, comprising: a first chamber formed by a first chamber floor, a first chamber ceiling, and at least one first chamber wall; a second chamber formed by a second chamber floor, a second chamber ceiling, and at least one second chamber wall, wherein: at least one of the first chamber ceiling and the second chamber ceiling further comprises an access opening fitted with an access opening cover, at least one of the first chamber ceiling or the at least one first chamber wall and the second chamber ceiling or the second chamber wall further comprises an influent opening, at least one of the first chamber floor or the at least one first chamber wall and the second chamber floor or the second chamber wall further comprises an effluent opening, the second chamber comprises a filtration media in proximity with the second chamber floor and an underdrain system in proximity with the second chamber floor, the at least one first chamber wall further comprises a first coupling opening and the at least one second chamber wall further comprises a second coupling opening, the first coupling opening and the second coupling opening are fitted together in a manner that places the first chamber and the second chamber in substantially leak-free fluid communication, the influent opening and the effluent opening are not both positioned in the first chamber or the second chamber, the first chamber floor, the first chamber ceiling, and the at least one first chamber wall are comprised of a material and a design adapted to form the first chamber in a manner that withstands pressure applied thereon by subterranean and ground surface materials that surround the underground bioretention system, and the second chamber floor, the second chamber ceiling, and the at least one second chamber wall are comprised of a material and a design adapted to form of the chamber in a manner that withstands pressure applied thereon by subterranean and ground surface materials that surround the underground bioretention system.
 18. The underground bioretention system of claim 17, further comprising live vegetation in the filtration media.
 19. The underground bioretention system of claim 18, further comprising an access riser and a reflective material mounted on an inner surface of at least one of a wall of the access riser, the at least one first chamber wall, and the at least one second chamber wall, and wherein the access opening cover is adapted to allow natural light to enter the chamber.
 20. The underground bioretention system of claim 18, further comprising an artificial light operative to emit an amount of light energy that promotes a growth of the live vegetation.
 21. The underground bioretention system of claim 18, further comprising at least one of a battery and a solar panel operative to supply electrical power to the artificial light. 